Fix interop tests by ensuring non-http-special metadata precedes other metadata

src/core/channel/compress_filter.c

@@ -200,7 +200,7 @@ static void process_send_ops(grpc_call_element *elem,
                 channeld->default_compression_algorithm;
             calld->has_compression_algorithm = 1; /* GPR_TRUE */
           }
-          grpc_metadata_batch_add_head(
+          grpc_metadata_batch_add_tail(
               &(sop->data.metadata), &calld->compression_algorithm_storage,
               grpc_mdelem_ref(channeld->mdelem_compression_algorithms
                                   [calld->compression_algorithm]));